The invention relates to a microphone for a hearing aid, the microphone comprising a housing with entrance means for letting pass sound waves into the housing, transducer means for converting the sound waves into an electrical signal, amplifier means for amplifying this electrical signal and connecting means for connecting the amplifier means with the terminals of a battery and for coupling the output signal of the amplifier means to a receiver. Such a microphone for example is disclosed in EP-A-0802700.
This invention also relates to a hearing aid including a body accommodating a microphone of the above type, a battery and a receiver.
Although hearing aids nowadays are much smaller than some years ago, while also the reliability and the sound quality have been improved, there still are some disadvantages that have to be overcome. Such disadvantages are for example the number of wires necessary to connect the microphone, amplifier, receiver and battery. These wires can influence negatively the reliability of the hearing aid and make the production thereof expensive. The wires are also at least part of the cause of interference by cellular phones and other radio frequency sources. Thus expensive solutions to prevent such interference are required. Another disadvantage is the size of the state of the art hearing aids, which is still too large to fit all ears with a Completely In the Canal (CIC) hearing aid.
In the state of the art hearing aids the microphone generally is an electret microphone with integrated CMOS or J-FET buffer. The amplifier comprises one or more discrete components and integrated circuits mounted on a hybrid printed circuit board. The receiver generally is a balanced armature receiver.
EP-A-0802700 describes a microphone, the housing of which includes a differential preamplifier.
DE-A-19545761 describes a proposal to integrate an A/D converter in a microphone for a hearing aid, while U.S. Pat. No. 4,592,087 and U.S. Pat. No. 4,689,819 propose to integrate the power amplifier in the microphone of a hearing aid.